(a) Field of the Invention
An exemplary embodiment of the present invention relates to a coupled inductor boost converter including another inductor coupled to an inductor of a boost converter, and driving method thereof.
Also, an exemplary embodiment relates to a switch control circuit included in a coupled inductor boost converter.
(b) Description of the Related Art
A boost converter (hereinafter, a coupled inductor boost converter) including a first inductor and a second inductor coupled to the first inductor generally operates according to a fixed switching frequency.
Particularly, the coupled inductor boost converter turns on a power switch according to a oscillator signal, which determines a switching frequency, and determining a turn-off time of the power switch by using an output voltage of the coupled inductor boost converter and a current flowing through the power switch.
During an off period of the power switch, a current flowing through the first inductor and the second inductor decreases with a slope according to a value of a voltage of the input voltage of the coupled inductor boost converter subtracted from the output voltage divided by an inductance.
However, when the power switch is turned on according to a fixed switching frequency in the condition of a low slope, hard switching in which a current flowing through the first inductor flows to the power switch occurs.
Also, when the power switch is turned on in a case of hard switching, an excessive voltage spike in a node (a drain of the power switch) between the first inductor and the second inductor can be generated by leakage inductance of the second inductor.
The prior coupled inductor boost converter should include a separate snubber circuit in order to prevent turn-off of the power switch by the voltage spike.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.